Interspecies Förster resonances of Rb-Cs Rydberg $d$-states for enhanced multi-qubit gate fidelities

We present an analysis of interspecies interactions between Rydberg $d$-states of rubidium and cesium. We identify the Förster resonance channels offering the strongest interspecies couplings, demonstrating the viability for performing high-fidelity two- and multi-qubit $C_{k}Z$ gates up to $k=4$, including accounting for blockade errors evaluated via numerical diagonalization of the pair-potentials. Our results show $d$-state orbitals offer enhanced suppression of intraspecies couplings compared to $s$-states, making them well suited for use in large-scale neutral atom quantum processors.